Progress 09/01/09 to 02/28/12
Outputs
OUTPUTS: The reactivity of phenolic compounds, specifically the hydroxycinammic acids in whole grain, on the mechanisms of the Maillard reaction and related flavor generation were investigated. In model systems the chemistry and fate of hydroxycinnamic acids (ferulic, p-coumeric, caffeic, sinapic, and cinnamic acid) in a glucose/glycine simulated baking model (10% moisture at 200C for 15 min) were defined. Liquid chromatography-mass spectrometry analysis of glucose/glycine and glucose/glycine/hydroxycinnamic acid model systems confirmed the phenolics reacted with Maillard intermediates; two main reaction product adducts were reported. On the basis of isotopomeric analysis, LC-MS, and NMR spectroscopy, structures of two ferulic acid-Maillard reaction products were identified. Aroma development in whole wheat versus refined wheat wheat was defined by comparative gas chromatography/olfactometry-aroma extract dilution analysis (GCO-AEDA) and subsequent quantitative gas chromatography/mass spectrometry-chemical ionization analysis utilizing stable isotope surrogate standards. Bitter compounds in whole wheat bread crust were characterized by sensory-guided fractionation techniques (most bitter portion of the bread sample) utilizing liquid-liquid extraction, solid-phase extraction, ultra-filtration and 2-D offline RPLC revealed multiple bitter compounds existed. The compounds with the highest bitterness intensities were selected and structurally elucidated based on accurate mass-TOF, MS/MS, 1D and 2D NMR spectroscopy. This project supported the research activities of two phd students. The findings of this work was also added to the lecture materials of two classes, food chemistry and flavor chemistry taught at the University of Minnesota. PARTICIPANTS: Marlene Moskowitz, PhD. Deshou Jiang, PhD., In Hee Cho (Post-Doc), Qing Bin TARGET AUDIENCES: Academics in food/agriculture science. Food/flavor Industry. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In the first phase of this project, hydroxycinnamic acids were reported to react with Maillard intermediates; two main reaction product adducts were reported 6-(4-hydroxy-3-methoxyphenyl)-5-(hydroxymethyl)-8 oxabicyclo[3.2.1]-oct-3-en-2-one (adduct I) and 2-(6-(furan-2-yl)-7-(4-hydroxy-3-methoxyphenyl)-1-methyl-3-oxo-2,5-di azabicyclo[2.2.2]oct-5-en-2-yl)acetic acid (adduct II). Both adducts I and II were suggested to be generated by pericyclic reaction mechanisms. The addition of these phenolic compounds also suppressed the generation of Maillard-type aroma compounds, such as furfurals, methylpyrazines, 2-acetylfuran, 2-acetylpyridine, 2-acetylpyrrole, and cyclotene as well as suppressed color development. In addition, adducts I and II suppressed the bacterial lipopolysaccharide (LPS)-mediated expression of two prototypical pro-inflammatory genes, inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2, in an in vitro murine macrophage model; ferulic acid reported negligible activity. The finds from phase 1 were translated to wheat bread. The influence of flour-type, 100% refined wheat or 100% whole wheat, on bread crust aroma was investigated. For refined bread crust (versus the whole wheat crust) five Maillard aroma compounds were reported to be higher in concentration, 2-acetyl-1-pyrroline, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 2-phenylethanol, 2-acetyl-2-thiazoline and acetylformoin by 4.0, 3.0, 2.1, 1.7, and 1.5-fold, respectively; whereas three compounds were at lower concentrations, 2-ethyl-3,5-dimethylpyrazine, (E,E)-2,4-decadienal and (E)-2-nonenal by 0.2, 0.5, and 0.5-fold, respectively. Evaluation of the bread crust by a trained sensory panel reported the perceived aroma intensity of the characteristic fresh refined bread crust aroma was significantly higher in the refined bread sample in comparison to the whole wheat sample; however when the five aroma compounds, that were higher in the refined bread crust, were added to the whole wheat crust at equivalent concentrations, no significant differences in the aroma intensity were observed. The liberation of ferulic acid from the whole wheat flour during the baking process was related to the observed reduction in the generation of these five aroma compounds in this sample, providing a novel understanding of mechanisms of flavor development in whole wheat bread. In the third phase of this project, bitter taste generation in whole wheat bread was also related to an alteration in Maillard chemistry by the native hydroxycinnamic acids in the flour. Bitterness in whole wheat bread can negatively influence product acceptability and consumption. The main bitter compounds in a commercial whole wheat bread product were identified as: Acortatarins C, Acortatarins D, 5-(hydroxymethyl)furfural (HMF), 2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one (DDMP), N-(1-deoxy-D-fructos-1-yl)-L-tryptophan (ARP), Tryptophol (TRO), 2-(2-formyl-5-(hydroxymethyl-1H-pyrrole-1-yl)butanoic acid (PBA) and Tryptophan (TRP). Based on the structures of these compounds, two main mechanisms of bitterness generation in wheat bread were supported, fermentation and Maillard pathways.
Publications
- Jiang, D., Chiaro, C., Maddali, P., Prabhu, K.S., Peteson, D.G. Identification of hydroxycinnamic acid-Maillard reaction products in low-moisture baking model systems. J. Agric. Food Chem. 2009, 57, 9932-9943.
- Jiang, D. and Peterson, D.G. 2010. Role of hydroxycinnamic acids on food flavor: a brief overview. Phytochem. Rev., 9, 187-193.
- Peterson, D.G. 2012. Refining Maillard-type flavor chemistry: Phenolic reaction pathways. In Advances and Challenges in Flavor Chemistry & Biology. 9th Wartburg Symposium Proceedings on Flavor Chemistry & Biology, Eisenach, Germany, pp 155-160.
- Moskowitz, M. and Peterson, D. G. 2011. Hydroxycinnamic acid-Maillard reactions in simple aqueous model systems. in Controlling Maillard Pathways. Washington, D.C.: American Chemical Society Symposium Proceedings 1042, pp 53-62
- Cho, I. H. and Peterson, D.G. 2010. Chemistry of bread aroma: A review. Food Sci. Biotechnol., 19, 575-582
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Progress 09/01/10 to 08/31/11
Outputs
OUTPUTS: Research focused on defining pathways of flavor development (taste and aroma) in whole wheat versus refined wheat flour formulated bread was conducted. These findings directly contributed to the objectives of the project - to define the role of food phenolics on flavor development. Previously we have reported that Hydroxycinnamic acids (HCAs) alter the Maillard reaction, a key mechanism of flavor development in processed food. In this phase of our USDA project we have extended our findings from model systems to actual bread products. The flavor of wheat bread made with refined versus whole-wheat flour was characterized by gas chromatography-olfactometry (GCO)-Aroma Extract Dilution Analysis (AEDA). The results from this work were presented at the American Chemical Society Meeting in Denver, CO and at the Weurman Flavour Symposium in Zaragoza, Spain. The results were also presented at the Flavor Research and Education Center at the University of Minnesota. PARTICIPANTS: Deshou Jiang, PHD Graduate student; Marlene Moskowitz, PHD Graduate student; Qing Bin, PHD Graduate Student TARGET AUDIENCES: Academics in food/agriculture science. Food Industry. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
For the first time we have demonstrated that the phenolic compounds in whole wheat flour can alter flavor generation in cereal foods. Key Maillard-type flavor generation pathways were found to be altered when bread was formulated with whole grain versus refined flavor. The phenolic compounds in whole wheat flour were found to alter the Maillard reaction and explain in part the typically lower flavor quality of whole wheat foods. Hydroxycinnamic acids (HCAs) have been suggested to contribute to the flavor properties of food by multiple mechanisms. Key differences were reported for 10 aroma compounds with high flavor dilutions (FD) between the two bread products. Based on GCO results, 2-acetyl-1-pyrroline, methional, 2-ethyl-3,5-dimethylpyrazine, furaneol, acetyl formoin, 2-acetyl-2-thiazoline and 2-phenylethanol showed higher FD values in a refined bread model. In contrast, methylpropanal, (E)-2-nonenal and (E,E)-2,4-decadienal showed higher FD values in a whole grain bread model. Isotopically labeled analogues for all 10 compounds were used for quantification purposes. Further synthesis of a 13C6-ferulic acid was also utilized to demonstrate the ability of HCA in the whole-wheat flour to trap key precursors of potent Maillard-type bread aroma compounds, such as 2-acetyl-1-pyrroline. Overall these findings provide a new basis to understand mechanisms of flavor development in whole-grain foods. This information facilitates the food industry to produce whole-grain products with higher flavor quality ultimately to promote their consumption and health impact.
Publications
- Moskowitz, M. and Peterson, D. 2010. Hydroxycinnamic Acid - Maillard Reactions in Simple Aqueous Model Systems. In Controlling Maillard Pathways to Generation Flavor. ACS symposium Series 1042, p. 52-62.
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